1. FIELD OF THE INVENTION
This invention relates to a downhole device which can be incorporated into the tubular drill string for transmitting torque to the bit and concurrently providing an indication of the torque transmitted.
2. DESCRIPTION OF THE PRIOR ART
In the drilling of subterranean wells, it is very desirable that the operator on the surface be apprised of the approximate torque at the rotating drill bit or in the tubular string. This requirement exists whether the drill bit is powered by a downhole motor or by a rotating drill string.
Also, since the speed of a downhole turbine motor is proportional to the generated torque, knowing the torque in this case will provide necessary information on the bit speed. By design, turbine bit speeds can be extremely high and if uncontrolled can lead to very rapid bit failure.
To directly measure the torque of a downhole drilling string is a difficult task, not only because the measurement must be effected at a distance ranging from 5000 to 10,000 feet or more from the surface but also the environmental conditions surrounding a downhole drilling string are not conducive to the utilization of conventional torque measuring devices. The shocks and impacts encountered by the drilling bit, accompanied with the fact that it is generally immersed in a drilling mud, prevents the application of conventional torque measuring equipment.